1. Field of the Invention
The invention relates to processes for the manufacture of monoalkanolamines and more particularly relates to the anhydrous production of monoalkanolamines over acidic, inorganic catalysts.
2. Description of Other Relevant Methods in the Field
Efforts in the production of monoalkanolamines have been primarily concerned with the manufacture of monoethanolamine (MEA) from the reaction of ammonia with ethylene oxide (EO). As early as 1897 it was demonstrated by Knorr that a small proportion of water is essential to this reaction since pure ethylene oxide does not react with anhydrous ammonia (Bev., 1897, vol. 30, p. 909 and 1899, vol. 32, p. 729). For a general background on this reaction, which shows a general acceptance that it should be run in the presence of water, see Ellis, Carleton, The Chemistry of Petroleum Derivatives, New York: Reinhold, Vol. 1, pp. 541-544 (1934) and Vol. 2, pp. 563, 567 (1937) and Miller, S. A., Ethylene and Its Industrial Derivatives, London: Ernest Benn Limited, pp. 16-17, 22, 632-635 (1969). The Kirk-Othmer Encyclopedia of Chemical Technology, Third Edition describes the standard manufacture of MEA from the reaction of ethylene oxide with an excess of aqueous ammonia at a temperature of about 50.degree. to 100.degree. C., see vol. 1, pp. 950-952 and vol. 9, p. 437.
Alkanolamines or cycloalkanolamines are produced from epoxyalkanes or epoxycycloalkanes which are reacted with ammonia and primary or secondary amines in the presence of heat, water and inert substances with large surface areas, according to Netherlands App. 6804616 [see Derwent Abstract, Vol. 5, No. 41, Gp 5,2 (1968)].
A number of schemes have been developed which use an acid as a catalyst or co-catalyst. U.S. Pat. No. 2,186,392 reveals that ethanolamines may be produced from ammonia or a primary amine and ethylene oxide and a salt of a weak acid, such as ammonium carbonate, in the presence of an aliphatic radical which is positive with respect to hydrogen, see Chemical Abstracts (CA) 36:4131-2. Tertiary amines with hydroxyalkyl radicals may be made from ammonia, primary or secondary amines and an alkylene oxide at a temperature from 30.degree. to 60.degree. C., with improved yields being possible if water or a weak acid is also present, see German Pat. No. 844,449 (CA 48:1429c). British Pat. No. 497,093 teaches that monoalkylolamines may be made from olefin oxides and ammonia in the presence of water and an acid (see CA 36:4131-8).
Aluminum oxide has also been tried as a catalyst. M. Sile, et al. in a series of two articles titled "Catalyst Reaction of Ethylene Oxide with Ammonia", found that ethylene oxide and ammonia may be reacted together at high temperatures (350.degree.-700.degree. C.) over aluminum oxide, phosphate catalysts and 13X zeolites to yield a large number of products of which ethanolamines were only a small part, including pyridine, alpha- and gamma-picolines, acetic acid, piperazine, aziridine, diethylamine, ethylenediamine and dioxane, see Latv. PSR Zinat. Akad. Vestis, Kim. Ser., Vol. 1972, parts 1 and 2, pp. 54-60 and 218-23, respectively, (CA 77:5243f and 88175j). More specifically, aluminum oxide at 350.degree. to 450.degree. gives pyridine, alpha- and gamma-picolines, acetic acid, alpha-aminoethanol and dioxane; zeolite 13X at 388.degree. to 450.degree. gave instead pyridine, alpha- and gamma-picolines, dioxane, piperazine and a little ethylenimine, diethylamine and ethylenediamine while different phosphates gave pyridine, alpha- and gamma-picolines, acetic acid, alpha-aminoethanol and ethylenimine. Similarly, M. S. Malinovskii in J. Applied Chem. (USSR), Vol. 20, pp. 630-634 (1947) teach ethylene oxide and ammonia may be reacted together over aluminum oxide at 300.degree. to 350.degree. C. to produce ethanolamines and an aldehyde (CA 42:1563c).
Even some anhydrous methods have been devised. U.S. Pat. No. 3,697,598 reveals that monoalkanolamines may be made from excess ammonia and alkylene oxides without water in the presence of a cationic ion exchange resin at a temperature of at least 80.degree. to 150.degree. C. This U.S. patent contains a description of Swedish Pat. No. 158,167 (to the same inventor) which concerns a reaction of alkylene oxides and ammonia in an anhydrous reaction system using as a catalyst organic and inorganic acids, ammonium salts and ion exchange resins. Anhydrous systems are desirable because the water removal step is eliminated. However, ion exchange resin catalysts are not as stable in high temperature situations as is desired. A high selectivity to the monoalkanolamine as opposed to the di- and trialkanolamine is also preferred. There is a need for a process having all of these advantages and none of the disadvantages.